Field of the Invention
This disclosure relates to a light emitting device and a resin composition.
Description of the Related Art
A light emitting diode (LED) is a semiconductor light emitting element produced from a metal compound such as gallium nitride (GaN). Various types of light emitting devices that emit light of, e.g., white color, incandescent bulb color, or orange color have been developed using such a semiconductor light emitting element in combination with a fluorescent material. Such light emitting devices are able to emit, e.g., white light by the light color mixture principle. Well known systems that emit white light include systems using a light emitting element that emits ultraviolet light and three types of fluorescent materials that emit red (R), green (G), and blue (B) light, and systems using a light emitting element that emits a blue light and a fluorescent material that emits, e.g., a yellow light. Light emitting devices that employ systems using a light emitting element that emits a blue light and a fluorescent material that emits, e.g., a yellow light are demanded in a wide variety of fields, including general lighting, car lights, displays, and backlights for liquid crystals. Of these, fluorescent materials used in light emitting devices for liquid crystal backlights are desired to have both superior light emission efficiency and superior color purity for reproducing colors over a wide range of the chromaticity coordinates. Fluorescent materials used in light emitting devices for liquid crystal backlights are particularly desired to be advantageously used in combination with color filters and to have an emission peak with a narrow half bandwidth.
Red-light emitting fluorescent materials that exhibit an emission peak with a narrow half bandwidth and having an excitation band in the blue region, include, for example, fluoride fluorescent materials having compositions such as K2AlF5:Mn4+, K3AlF6:Mn4+, K3GaF6:Mn4+, Zn2AlF7:Mn4+, KIn2F7:Mn4+, K2SiF6:Mn4+, K2TiF6:Mn4+, K3ZrF7:Mn4+, Ba0.65Zr0.35F2.70:Mn4+, BaTiF6:Mn4+, K2SnF6:Mn4+, Na2TiF6:Mn4+, Na2ZrF6:Mn4+, KRbTiF6:Mn4+, or K2Si0.5Ge0.5F6:Mn4+ (see, e.g., Japanese Patent Application prior-to-examination Publication (kohyo) No. 2009-528429).
To protect the light emitting element and other components of a light emitting device, the light emitting element as well as wires and the other cables are encapsulated within an encapsulation material that contains fluorescent material particles.